We set the BVF searching parameters for the FUGIN \({\rm CO}\)  J=1–0 data as follows: maximum spatial size of 10 \(\rm {pc}\) , minimum velocity width of 5 km s\(^{-1}\)  in full-width at zero-intensity (FWZI), and minimum main beam temperature 1 K (\(\sim \!1\sigma \) ). We also define the FWZI size parameter of each BVF by \(\Delta S= D\rm {tan}(\sqrt{\Delta {\textit {l}\,}\Delta {\textit {b}}}\) ), where \(\Delta l\)  (\(\Delta b\) ) is the FWZI extent of the BVF in \(l\)  (\(b\) ) and \(D\)  is the distance to the parent cloud. Here we calculated the kinematic distance using the rotation curve described in [1]}. The Galactic constants are taken to be \(R_{0}= 8.0\ \rm {kpc}\)  and \(V_{0}= 200\ \rm {km\ s^{-1}}\)  in this paper (e.g., [1]}, [3]}). For simplicity, the near-distance was employed in this study. Employing the far-distance gives an upward revision to \(\Delta S\)  by up to a factor of 10. The maximum size was set to be consistent with the definition of an HVCC [4]}. The employed minimum velocity width of 5 km s\(^{-1}\)  is factor of 2\(\sim \) 3 broader than those of `normal’ molecular clouds that have the same sizes as the BVFs in the Galactic disk. This criterion is roughly consistent with that for HVCCs in the CMZ, where normal molecular clouds have velocity widths of \(\sim \) 20 km s\(^{-1}\) .
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